This invention is directed to a single-ply roofing membrane having a nonwoven laminated thereto (laminated membrane), the roof system using the laminated membrane, the method of installing the roofing system, and the nonwoven material laminated to the membrane.
In commercial, flat roofs, there are three popular roofing systems in use today. Those roofing systems are: built-up roofs (BUR), modified bitumen, and single-ply or membrane roofing systems. The commercial flat roof market is divided roughly equally between those three roofing systems.
Single-ply roofing systems are known. Single-ply laminated membranes are known. For example, see U.S. Pat. Nos. 5,456,785, 5,620,554, and 5,643,399. Typically, these laminated membranes comprise a membrane, made from EPDM or other thermoplastic material, and a nonwoven (or fleecy material) adhered on one surface of the membrane. The nonwoven material is provided to facilitate adherence of the membrane, via an asphalt (or bitumen) or a proprietary adhesive formulation, to the sub-roof structure. The commercially available, laminated membranes have been readily accepted by the market, when used with the proprietary adhesive formulation. Acceptance by roofers wishing to use asphalt as the adherent, however, has been slower. The problem hindering acceptance in asphalt adhered systems is known as xe2x80x9cstrike through.xe2x80x9d Strike through arises when the asphalt is spread over a roof or roof decking, and the laminated membrane is laid into the molten asphalt. If the asphalt application is too thick, the asphalt can saturate the fleece layer and come into contact with the polymer membrane. Some components of the molten asphalt, a petroleum based material, are absorbed by the membrane causing swelling and discoloration of the membrane. The swelling and discoloration are visible, after the laminated membrane is installed, and are considered an installation defect.
One solution to the strike through problem is set forth in U.S. patent application Ser. No. 09/238,678 filed on Jan. 26, 1999, inventor S. R. Clarke, assigned to Carlisle Syntec. The solution disclosed therein consists of a membrane laminate in which a membrane sheet and a nonwoven layer sandwich a protective layer. The protective layer is a discrete layer or film (i.e., not a part of the nonwoven) made of a material resistant to the components of the molten asphalt (i.e., polyester, polyurethane, polyetherurethane, and the like).
Accordingly, there is a need for a membrane laminate for use in asphalt adhered single-ply laminated roofing systems that eliminates or reduces the occurrence of xe2x80x9cstrike through.xe2x80x9d
This invention is directed to a membrane laminate for a roofing system comprising a membrane sheet and a nonwoven material laminated to said sheet. The nonwoven material has a semipermeable, skinned layer formed therein.